What is Electromagnetic Spectrum ?

- September 23, 2020

ELECTROMAGNETIC SPECTRUM :

As the sun sends its rays to Earth, it lights up our world. But there's more to the world than the things we can see with light alone.

As light races through space, it makes electricity and magnetism ripple down its path like waves on the sea. Light is not the only energy that behaves like this: there's a whole collection of similar waves called the Electromagnetic Spectrum. Some of these waves are very long, with large spaces from one peak to the next. Others are extremely short and close to each other. Different waves have different uses, depending on their length.

Although we can't see most electromagnetic waves, they are incredibly useful, helping us with everything from spotting broken bones to watching TV shows.

WHERE ELECTROMAGNETIC RADIATION COMES FROM:

Light is made when atoms flash on and off like fireflies. If you hear an iron bar, it goes red hot. The atoms inside absorb heat energy, but it makes them unstable. To return to normal, they have to get rid of the energy again, and do so by giving off a flash of light. Other kinds of electromagnetic waves are made in the same way.

On your wavelength:

The largest waves on the electromagnetic spectrum are radio waves, which can be thousands of kilometers long from the top of the one wave to the next. At the other end of the spectrum, gamma Ray's are even smaller than atoms, and are packed full of energy. The shortest waves have the most energy and the highest frequency (meaning they vibrate the fastest), while the longest waves vibrate more slowly and have less energy. As you travel along the spectrum you can see how different wavelengths are used for a variety of useful tasks.

Radio waves:

Radio waves carry TV (as well as radio) signals between giant antennas like this one. Long (AM) radio waves bounce off part of Earth's atmosphere called the ionosphere, especially at night, which is why you can pick up more international radio stations in the evening.

Microwaves:

One microwave is typically about as long as a pen. Like other electromagnetic waves, they race along at the speed of light, which makes them perfect for carrying phone calls and internet data.

Infrared rays:

We feel the heat that things give off when the atoms in our bodies absorb a kind of "hot light" called infrared radiation. Although invisible, infrared radiation shows up on thermal ( heat-sensitive) cameras, like the one that photographed this elephant.

Ultraviolet:

Shorten blue light waves and you get ultraviolet (UV). Sunlight contains two kinds of ultraviolet: UV-A and the more harmful UV-B. Small amounts of UV give a nice suntan; in bigger does, it ages skin and causes cancer.

X-rays:

These short waves have enough energy to pass through soft body tissues (skin and muscles) but not bone. That's why an X-ray photo shows bones as shadows. High doses of X-rays can be very harmful.

Gamma rays:

The smallest electromagnetic waves are like super-energetic X-rays, but do much more damage to the human body. They're made when atoms split apart in nuclear explosions.

THE VISIBLE OR COLOR SPECTRUM:

The light that looks white to our eyes is really a mixture of different colours. We can see this by firing a light beam through a wedge-shaped piece of glass called a prism, which causes light to spread into Spectrum. Rainbows work in exactly the same way. As sunlight shines through rain, each water droplet acts like a miniature prism.